Removal of Zn+2 and Pb+2 from Wastewater by using Natural Nano Montmorillonites

Okan Duman, Celalettin Özdemir, Atila Demiröz, Muhammed Kamil Oden

Abstract

In this study, nano montmorillonite which is an economic and naturally abundant material was investigated in terms of its adsorption capability to remove lead and zinc ions from aqueous solutions. A series of experiments were performed at various temperatures such as 250C, 350C, 450C. The experimental results of potential adsorption belonging to lead and zinc ions were evaluated by using Langmuir, Freundlich and Temkin isotherm models. According to the data obtained, adsorption of both metal ions was well fitted with Langmuir isotherm model. In the adsorption of lead and zinc ions by nano montmorillonite, effects of adsorbent dosage, stirring speed, pH, reaction time, temperature and initial concentration were investigated. According to the results, the highest removal efficiency for lead ions was achieved with 0.25 g nano montmorillonite, 200 rpm stirring speed, pH 5, 200 mg/L initial concentration, 120 minutes and 84% removal efficiency was obtained. For zinc ions, 81% removal efficiency was obtained with 0.3 g nano montmorillonite, 200 rpm stirring speed, pH 5, 200 mg/L initial concentration and 180 minutes. For both metal ions, thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 were calculated and it was determined that adsorption process was spontaneous and endothermic. Moreover, adsorption kinetics was considered and this process was fitted well with pseudo-second order kinetic model. In accordance with the results of this study, it can be concluded that adsorption capability of nano montmorillonite for the removal of heavy metals from aqueous solutions is quite high.